More graceful shutdown using Kernel.exit and rescuing SystemExit.
Merge pull request #45 from ryanjohns/signal_handling

More graceful shutdown using Kernel.exit and rescuing SystemExit.
Bump to version 0.4.3
Add license to file (Closes #46)
Fix logger example for HOOKS
Fix travis for backburner
Allow rbx failure
Tweak travis yml typo